Method of making sodium sulfate.



insirnn srarnts Parana clarion.

.IUllh' l). llfiNNOUli, OISYlL JUSIG, NEW YORK, ASSIUNOR TO THE SOLVAYPROCESS (UM PAN Y,

' A (.ORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented May 18, 1909.

Application filed May 25, 1906. Serial No. 318,605.

' To all whom it may concern:

Be it known that I, JOHN D. PENNooK, a citizen of the United States,residing at Syracuse, in the county of Onondaga and State of New York,have invented a new and useful Method of Making Sodium Sulfate, of whichthe following is a specification.

This invention relates to the manufacture of sodium sulfate.

The object of the invention is to provide an economical and eifectivemethod of converting commercial niter cake) or acid sodium sulfate,HNaSO into sodium sulfate. As is well known, acid sodium sulfate isproduced in large quantities in the form of niter cake in themanufacture of nitric acid and is at the present time substantially awaste product. It has heretofore been proposed to convert this intosodium sulfate by various methods, none of which have provensufliciently advantageous to insure general adoption.

According to this process the niter cake, commonly containing theequivalent of about 36 per cent. of free sulfuric. acid, is mixed with asuitable sodium compound having an alkaline reaction, as sodium hydi ateor carbonate, or with a mixture containing the same. The sodium compoundshould be used in substantially the theoretical proportion required toneutralize the sulfuric acid .present, and the mixture should beintimate, this being preferably effected by grinding the materialstogether. To the mixture so prepared the minimum quantity of water whichwill suiiice to thoroughly moisten it and to effect a complete reactionbetween the acid and alkaline components is added and thoroughlyincorporated.

I prefer to proceed substantially as follows :Commercial niter cakecontaining about 90 per cent. of acid sodium sulfate and 9 per cent. ofnormal sodium sulfate is ground with soda'ash, the propoftions beingapproximately 1000 pounds niter cake to 398 pounds soda ash. Theresulting intimate mixture is moistened and thoroughly stirred,preferably in a suitable mechanical stirrer, until the reaction iscomplete, when it is dried. The amount of water required will generallybe 18 to 20 per cent. by weight. Instead of soda ash as above described,

I may use for neutralizing the acid sulfate the roduct known in the artas fished salts and consisting substantially of a hy drated mixture ofsodium hydroxid carbonate and sulfate in I proportions approximately asshown by the following analysis:

In" this case both the sodium hydroxid and carbonate neutralize thesulfuric acid with production of sodium sulfate. On account of the highpercentage of sulfate in fished salts a much larger proportion must beemployed than in the case of soda ash, viz., 640 pounds fished salts toeach 1000 pounds niter cake.

The method as above described presents decided advantages in that thequantity of water added is the minimum quantitycapable of givingreacting conditions, from which it follows that the expense ofevaporation is reduced to t he practicable minimum. The necessaryreaction between the acid and alkaline components of the mixture mayalso be brought about by subjecting the same to a temperature above onehundred and twenty-five degrees centigradc. It is thought however, thata more efficient reaction is effected by moistening the mixture,

since the free acid thereby becomes very active and consequentlyattack'tthe carbonate .of soda more readily.

\VhatI claim is 1. The method of makingsodium sulfate, which consists inmixing niter cake and a sodium compound, having an alkaline reaction, inapproximately reacting proportions, then effecting a reaction betweenthe acid and alkaline components and recovering the resulting sodiumsulfate.

2. The method of making sodium sulfate which consists in mixing nitercake and a sodium compound capable of neutralizing the same inapproximately reacting proportions, then moistening the mixture andthereby effecting reaction in presence of undissolved salts, and dryingand recovering the resulting sodium sulfate, substantially as described.

3. The method of making sodium sulfate, which consists in mixing nitercake and a sodium compound capable of neutralizing the same inapproximately reacting proportions, then adding the minimum quantity ofwater capable of giving reacting conditions, and drying and recoveringthe resulting sodium sulfate, substantially as described. H

4, The method of making sodium sulfate, which consists in mixing nitercake and a sodium compound capable of neutralizing the same inapproximately reacting proportions, then adding the minimum quantity 1of water capable of givingreacting condi tious, stirring the mixtureuntil reaction is complete and drying and recovering the resultingsodium sulfate, substantially as described.

5.'The method of'making sodium sulfate, Which consists in mixing nitercake and fished salts in approximately reacting proportions, then addingWater and thereby effecting reaction in presence of undissolved salts,and drying and recoverin' the resulting sodium sulfate, substantia ly asdescribed.

JOHN D. PENNOGK.

lVitnesses Rom. CRox'snALE, EUGENE E. Youxo.

